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chaotic, typically you mark a chosen answer to your question as correct by clicking the checkmark next to it. Please do so; it helps motivate users to leave thorough answers and will help you get accurate answers to future questions.
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kevbohMay 7 '11 at 19:46

EDIT moved from a comment and added to this answer at the suggestion of @Neil Fein:

It's a professional presentation, you're a professional, so act like one. The best opening, imo, is "what I'm going to talk about." Anything else looks like you're apologizing for stealing their valuable time; if that were true, they wouldn't be in the audience. If you try for humor, it had better be sure-fire and guaranteed to bring a laugh, otherwise you will look as foolish, inept, and unprofessional as every other presenter who ever tried the exact same thing. Just imo.